Integrated optics beam deflectors and systems

ABSTRACT

This invention discloses a monolithic optical light modulator including a substrate having formed monolithically thereon a modulator and a light detector providing a modulating output to said modulator.

This application is a continuation of Ser. No. 10/057,787 filed Jan. 24,2002 which is a continuation of Ser. No. 09/470,640 filed Dec. 22, 1999U.S. Pat. No. 6,374,002 which is a Division of Ser. No. 09/470,642 filedDec. 22, 1999 now U.S. Pat. No. 6,366,710 which is a continuation ofPCT/IL98/00293 filed Jun. 23, 1998.

FIELD OF THE INVENTION

The present invention relates to integrated optics beam deflectors andto systems, such as scanners and optical switches, employing suchdeflectors.

BACKGROUND OF THE INVENTION

Various types of integrated optics beam deflectors are known in the art.U.S. Pat. No. 5,239,598, the disclosure of which is hereby incorporatedby reference, and the references cited therein, as well as the followingarticles are believed to represent the state of the art:

Katz et al, Phase-locked semiconductor laser array with separatecontacts, Appl. Phys. Lett 43, 1983, pp 521-523;

Vasey et al, Spatial optical beam steering with an AlGaAs integratedphased array, Applied Optics, 32, No. 18, Jun. 20, 1993, pp 3220-3232.

SUMMARY OF THE INVENTION

The present invention seeks to provide an improved light beam deflectorand systems employing same.

There is thus provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding:

at least one substrate having formed thereon a multiplicity ofwaveguides, each waveguide receiving light and emitting light, thetotality of light emitted by the multiplicity of waveguides producing atleast one selectably directable output beam; and

at least one sequential multiplexer applying electrical inputs to the atleast one substrate for individually controlling the light emitted byeach of the multiplicity of waveguides, thereby governing theorientation of the selectably directable output beam.

Preferably, the at least one sequential multiplexer is a phasecontroller which controls the phase of the light emitted by each of themultiplicity of waveguides.

Alternatively or additionally, the at least one sequential multiplexeris an intensity controller which controls the intensity of the lightemitted by each of the multiplicity of waveguides.

In accordance with a preferred embodiment of the present invention, theat least one substrate includes a plurality of substrates, each havingformed thereon a multiplicity of waveguides, each waveguide receivinglight and emitting light and wherein the at least one sequentialmultiplexer applies electrical inputs to the plurality of substrates.

There is also provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding:

a plurality of substrates, each having formed thereon a multiplicity ofwaveguides, each waveguide receiving light and emitting light, thetotality of light emitted by the multiplicity of waveguides: producingat least one selectably directable output beam.

Further in accordance with a preferred embodiment of the presentinvention there is provided a selectably directable optical beamgenerating device including:

a light source;

at least one substrate having formed thereon a multiplicity ofwaveguides, each waveguide receiving light from the light source andemitting light, the totality of light emitted by the multiplicity ofwaveguides producing at least one selectably directable output beam; and

Preferably the light source includes a laser formed on the at least onesubstrate:

at least one sequential multiplexer applying electrical inputs to the atleast one substrate for individually controlling the light emitted byeach of the multiplicity of waveguides, thereby governing theorientation of the selectably directable output beam.

Preferably, the at least one sequential multiplexer is a phasecontroller which controls the phase of the light emitted by each of themultiplicity of waveguides.

Alternatively or additionally, the at least one sequential multiplexeris an intensity controller which controls the intensity of the lightemitted by each of the multiplicity of waveguides.

Preferably, the at least one substrate includes a plurality ofsubstrates, each having formed thereon a multiplicity of waveguides,each waveguide receiving light and emitting light and wherein the atleast one sequential multiplexer applies electrical inputs to theplurality of substrates.

Additionally in accordance with a preferred embodiment of the presentinvention there is provided a selectably directable optical beamgenerating device including:

at least one light source; and

a plurality of substrates, each having formed thereon a multiplicity ofwaveguides, each waveguide receiving light from the at least one lightsource and emitting light, the totality of light emitted by themultiplicity of waveguides producing at least one selectably directableoutput beam.

Still further in accordance with a preferred embodiment of the presentinvention there is provided a selectably directable optical beamdeflecting device including:

at least one substrate having formed thereon a multiplicity ofwaveguides; and

a microlens array receiving light and coupling the received light to themultiplicity of waveguides.

Additionally in accordance with a preferred embodiment of the presentinvention there is provided a selectably directable optical beamgenerating device including:

a light source;

at least one substrate having formed thereon a multiplicity ofwaveguides; and

a microlens array receiving light from the light source and coupling thereceived light to the multiplicity of waveguides.

There is also provided in accordance with another preferred embodimentof the present invention a selectably directable optical beam generatingdevice including a light source, at least one substrate having formedthereon a multiplicity of waveguides and a microlens array receivinglight from the light source and coupling the received light to themultiplicity of waveguides.

Preferably the selectably directable optical beam generating deviceprovides wavelength division multiplexing.

There is also provided in accordance with another preferred embodimentof the present invention an optical device including at least onesubstrate having formed thereon a multiplicity of polarizationindependent, electrically controlled waveguides, and a light receiverdirecting light into the multiplicity of waveguides.

Further in accordance with a preferred embodiment of the presentinvention each one of the multiplicity of polarization independent,electrically controlled waveguides includes first and second phaseshifting waveguide portions.

Still further in accordance with a preferred embodiment of the presentinvention the electric fields of different directions are applied to thefirst and second phase shifting waveguide portions.

Preferably each of the multiplicity of polarization independentelectrically controlled waveguides includes first and secondphase-shifting waveguide portions of respective first and second lengthshaving respective first and second electric fields of differentdirections applied thereto.

Additionally in accordance with a preferred embodiment of the presentinvention at least one of the multiplicity of polarization independent,electrically controlled waveguides includes first and second phaseshifting waveguide portions separated by a quarter-wave plate, wherebylight from the first waveguide portion passes through the quarter-waveplate prior to entering the second waveguide portion.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical device including at least one substratehaving formed thereon a multiplicity of electrically controlledwaveguides, and a light receiver for directing light into themultiplicity of waveguides, the light receiver including a selectablepolarization rotator.

There is also provided in accordance with yet another preferredembodiment of the present invention an optical device including at leastone substrate having formed thereon a multiplicity of electricallycontrolled waveguides, and a polarization rotator for rotating thepolarization of light passing through the multiplicity of electricallycontrolled waveguides by 90 degrees or an odd integer multiple thereof.

Further in accordance with a preferred embodiment of the presentinvention the polarization rotator operates by generating a magneticfield extending parallel to longitudinal axes of the multiplicity ofwaveguides.

Still further in a accordance with a preferred embodiment of the presentinvention the selectable polarization rotator is automatically operativeto rotate the polarization so as to provide an optimized light outputfrom the multiplicity of waveguides.

Additionally in accordance with a preferred embodiment of the presentinvention the selectable polarization rotator is responsive to an outputof the multiplicity of waveguides.

Moreover in accordance with a preferred embodiment of the presentinvention the selectable polarization rotator is responsive to thepolarization of an input to the multiplicity of waveguides.

Further in accordance with a preferred embodiment of the presentinvention and having selectably directable beam deflectionfunctionality. Alternatively, the selectably directable beam deflectionfunctionality includes directable beam receiving functionality.

Further in accordance with a preferred embodiment of the presentinvention and the selectably directable functionality is realized bymeans of phase-shifting.

There is also provided in accordance with yet another preferredembodiment of the present invention an optical device including at leastone substrate having formed thereon a multiplicity of electricallycontrolled waveguides, and a light receiver directing light into themultiplicity of waveguides and including polarization maintainingoptical fibers.

There is also provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding at least one substrate having formed thereon a multiplicity ofphase-shifting waveguides, and a light receiver directing light into themultiplicity of waveguides, and wherein the at least one substrateincludes multiple mutually insulated conductor layers including amultiplicity of conductors, at least some of which are connected to thewaveguides by vias.

There is provided in accordance with another preferred embodiment of thepresent invention a selectably directable optical beam generating deviceincluding at least one substrate having formed thereon a multiplicity ofwaveguides, and a laser monolithically formed on the at least onesubstrate and providing light to the multiplicity of waveguides.

There is provided in accordance with a preferred embodiment of thepresent invention an optical device including at least one substratehaving formed thereon a multiplicity of waveguides, and a lasermonolithically formed on the at least one substrate and providing lightto the multiplicity of waveguides, the multiplicity of waveguides andthe laser being formed at different regions of identical layers.

There is provided in accordance with yet another preferred embodiment ofthe present invention a semiconductor laser including an N-doped galliumarsenide substrate, an N-doped aluminum gallium arsenide layer formedover the substrate, an N-doped gallium arsenide layer formed over theN-doped aluminum gallium arsenide layer, a P-doped gallium arsenidelayer formed over the N-doped gallium arsenide layer, a P-doped aluminumgallium arsenide layer formed over the P-doped gallium arsenide layer,and a P-doped gallium arsenide layer formed over the P-doped aluminumgallium arsenide layer.

There is provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding at least one substrate having formed thereon a multiplicity ofwaveguides, and a light receiver coupling light to the multiplicity ofwaveguides at first ends thereof and wherein the multiplicity ofwaveguides are outwardly tapered at the first ends thereof.

There is also provided in accordance with yet another preferredembodiment of the present invention a selectably directable optical beamdeflecting device including at least one substrate having formed thereona multiplicity of waveguides, and a light receiver directing light intothe multiplicity of waveguides, the light receiver including acylindrical lens.

There is also provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding at least one substrate having formed thereon a multiplicity ofwaveguides, and a light receiver directing light into the multiplicityof waveguides, the light receiver including a multi-mode interferencecoupler.

There is also provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding at least one substrate having formed thereon a multiplicity ofwaveguides, and a light receiver directing light into the multiplicityof waveguides, the light receiver including a planar wave guide.

Further in accordance with a preferred embodiment of the presentinvention the multiplicity of waveguides have first ends which abut theplanar waveguide, the first ends being tapered outwardly.

Still further in accordance with a preferred embodiment of the presentinvention the multi-mode interference coupler includes a light receivingwaveguide. Preferably the light receiving waveguide includes a lightreceiving end which is outwardly tapered.

Additionally in a accordance with a preferred embodiment of the presentinvention the light receiving waveguide includes an electro-absorptionmodulator.

Moreover in accordance with a preferred embodiment of the presentinvention the electro-absorption modulator receives a modulating inputfrom a light detector monolithically formed therewith on the at leastone substrate.

Additionally or alternatively the multiplicity of waveguides iscontrollable so as to selectably provide multiple selectably directedoutput beams.

There is also provided in accordance with a preferred embodiment of thepresent invention a selectably directable optical beam deflecting deviceincluding at least one substrate having formed thereon a multiplicity ofwaveguides, and a light receiver directing light into the multiplicityof waveguides, and wherein the multiplicity of waveguides iscontrollable so as to selectably provide multiple selectably directedoutput beams.

Additionally or alternatively the optical device also includes awaveguide filter including a necked waveguide having a relatively broadinput end which receives light and allows propagation of multi-modelight waves therethrough, a narrowed neck portion at which higher modesradiate outside the waveguide and only the modes which can propagatetherethrough pass therethrough, and a relatively broad output end.

There is also provided in accordance with a preferred embodiment of thepresent invention a waveguide filter including a necked waveguide havinga relatively broad input end which receives light and allows propagationof multi-mode light waves therethrough, a narrowed neck portion at whichhigher modes radiate outside the waveguide and only the modes which canpropagate therethrough pass therethrough, and a relatively broad outputend.

Preferably the optical device is implemented on gallium arsenide.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical switch including a monolithic plurality ofselectably directable optical beam deflecting devices, a plurality ofoptical beam receiving devices.

There is also provided in accordance with yet another preferredembodiment of the present invention an optical switch including aplurality of monolithic pluralities of selectably directable opticalbeam deflecting devices, a plurality of optical beam receiving devices.

Further in accordance with a preferred embodiment of the presentinvention the plurality of monolithic pluralities of beam deflectingdevices are arranged generally parallel to one another along an axisperpendicular to a plane in which selectable deflection of a light beamis produced thereby.

Still further in accordance with a preferred embodiment of the presentinvention the plurality of monolithic pluralities of beam deflectingdevices are arranged generally distributed along a curve extending in aplane perpendicular to a plane in which selectable deflection of a lightbeam is produced thereby.

There is also provided in accordance with yet another preferredembodiment of the present invention an optical switch including aplurality of selectably directable optical beam deflecting devices, eachincluding at least one substrate having formed thereon a multiplicity ofwaveguides, and a plurality of optical beam receiving devices.

Further in accordance with a preferred embodiment of the presentinvention each of the plurality of optical beam receiving devicesincludes an optical fiber. Preferably the optical fiber has a numericalaperture of less than 0.3.

Additionally in accordance with a preferred embodiment of the presentinvention the selectably directable optical beam deflecting devices eachinclude at least one substrate having formed thereon a multiplicity ofwaveguides.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical switch including a plurality of opticalbeam emitting devices and a monolithic plurality of selectablydirectable optical beam receiving devices. Preferably the optical beamreceiving devices are selectably directable.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical switch including a plurality of opticalbeam emitting devices and a plurality of monolithic pluralities ofselectably directable optical beam receiving devices.

Further in accordance with a preferred embodiment of the presentinvention the plurality of monolithic pluralities of beam receivingdevices are arranged generally parallel to one another along an axisperpendicular to a plane in which selectable deflection of a light beamis produced thereby. Alternatively the plurality of monolithicpluralities of beam receiving devices are arranged generally distributedalong a curve extending in a plane perpendicular to a plane in whichselectable deflection of a light beam is produced thereby.

Still further in accordance with a preferred embodiment of the presentinvention the selectable directable optical beam receiving devices eachinclude at least one substrate having formed thereon a multiplicity ofwaveguides.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical switch including a plurality of opticalbeam emitting devices, and a plurality of selectably directable opticalbeam receiving devices, each including at least one substrate havingformed thereon a multiplicity of waveguides.

Additionally in accordance with a preferred embodiment of the presentinvention both the optical beam emitting devices and the optical beamreceiving devices are selectably directable.

Moreover in accordance with a preferred embodiment of the presentinvention and including a light input coupler to the plurality ofoptical beam devices and a cylindrical lens light output couplerreceiving light from the plurality of optical beam devices. Preferablythe cylindrical lens light output coupler includes a plurality ofcylindrical lenses, each associated with an optical beam device.Alternatively the cylindrical lens light output coupler includes asingle cylindrical lens associated with a plurality of optical beamdevices.

Additionally in accordance with a preferred embodiment of the presentinvention and including a light input coupler to the plurality ofoptical beam devices which includes at least one cylindrical lens.Preferably the light input coupler to the plurality of optical beamdevices includes at least one cylindrical lens.

Moreover in accordance with a preferred embodiment of the presentinvention the at least one cylindrical lens includes a plurality ofcylindrical lenses, each associated with an optical beam device.

Still further in accordance with a preferred embodiment of the presentinvention the at least one cylindrical lens includes a singlecylindrical lens associated with a plurality of optical beam devices.

Further in accordance with a preferred embodiment of the presentinvention the light input coupler also includes a multiplicity ofmicrolenses fixed with respect to the at least one cylindrical lens,each of the multiplicity of microlenses directing light into a singlebeam transmitting device.

Preferably the multiplicity of microlenses includes focusingmicrolenses. Alternatively the multiplicity of microlenses includescollimating microlenses.

There is also provided in accordance with a preferred embodiment of thepresent invention an active optical beam transmission device includingat least one substrate having formed thereon a multiple layer integratedelectronic circuit, and a multiplicity of electrically controlledwaveguides.

Further in accordance with a preferred embodiment of the presentinvention the waveguides emit a selectably directable beam of light.Alternatively or additionally the waveguides selectably receive a beamof light.

Still further in accordance with a preferred embodiment of the presentinvention the multiplicity of waveguides are operative simultaneously todeflect a plurality of optical beams.

Preferably overlying the waveguides, a multiplicity of electricalcontacts, each contact providing an electrical connection to at leastone of the multiplicity of electrically controlled waveguides.

There is also provided in accordance with a preferred embodiment of thepresent invention an active optical beam transmission device includingat least one substrate having formed thereon a plurality of waveguideassemblies, each including a multiplicity of electrically controlledwaveguides, and overlying each of the waveguide assemblies, amultiplicity of electrical contacts, each contact providing anelectrical connection to at least one of the multiplicity ofelectrically controlled waveguides in the assembly.

There is also provided in accordance with a preferred embodiment of thepresent invention a monolithic optical light modulator including asubstrate having formed monolithically thereon an electro-absorptionmodulator, and a light detector providing a modulating output to theelectro-absorption modulator.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical waveguide-lens including at least onesubstrate having formed thereon a multiplicity of electricallycontrolled, phase-shifting waveguides, and an electrical control signalsource providing electrical signals to the multiplicity of waveguides tocause them to have a desired lens functionality.

Additionally the optical devices described hereinabove may also includean electrical control signal source providing electrical signals to themultiplicity of waveguides to cause them to have a desired lensfunctionality. Furthermore the optical devices may also include afeedback connection between the optical beam receiving devices and theoptical beam deflecting devices.

Still further in accordance with a preferred embodiment of the presentinvention the optical beam receiving devices are configured to receivelight over a region sufficiently large such that wavelength dependenciesof the deflectors do not substantially affect the amount of light sensedby the receiving devices.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical switch including a plurality of selectablydirectable optical beam deflecting devices, a plurality of optical beamreceiving devices, and wherein the plurality of selectably directableoptical beam deflecting devices and the plurality of optical beamreceiving devices are monolithically formed on the same substrate.

Further in accordance with a preferred embodiment of the presentinvention the plurality of selectably directable optical beam deflectingdevices and the plurality of optical beam receiving devices aremonolithically formed on the same substrate.

There is also provided in accordance with a preferred embodiment of thepresent invention a method of forming a monolithic structure havingelectrical contacts including the steps of configuring regions on awafer such that upper and lower surfaces are defined thereon, coatingthe upper and lower surfaces with metal by evaporation in a directiongenerally perpendicular to the upper and lower surfaces, the directionbeing selected with respect to interconnecting surfaces whichinterconnect the upper and lower surfaces such that metal is notsubstantially coated onto the interconnecting surfaces, wherebyelectrical connections between the upper and lower surfaces via theinterconnecting surfaces are not formed by the metal coating.

Further in accordance with a preferred embodiment of the presentinvention the monolithic structure includes a waveguide device.

There is also provided, in accordance with yet another preferredembodiment of the present invention a method for aligning a waveguidedevice including providing a waveguide having light emitting capability,and operating the waveguide to emit light during alignment thereof.

There is also provided in accordance with a preferred embodiment of thepresent invention an optical switch including a plurality of ports, anoptical crossbar assembly, and a plurality of information carryingoptical fibers interconnecting the plurality of ports with inputs to theoptical crossbar assembly, the information carrying optical fibersincluding polarization maintaining fibers.

There is also provided in accordance with yet another preferredembodiment of the present invention an optical switch including aplurality of ports, an optical crossbar assembly, and a plurality ofinformation carrying optical fibers interconnecting the plurality ofports with inputs to the optical crossbar assembly, the plurality ofports each having an input and output which are clock synchronized.

Additionally in a accordance with a preferred embodiment of the presentinvention the plurality of ports are clock synchronized amongthemselves.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be understood and appreciated more fully fromthe following detailed description, taken in conjunction with thedrawings in which:

FIG. 1 is a simplified illustration of laser writing apparatusconstructed and operative in accordance with a preferred embodiment ofthe present invention;

FIG. 2 is a simplified illustration of a scanning engine suitable foruse in the laser writing apparatus of FIG. 1;

FIGS. 3A and 3B illustrate two alternative embodiments of an integratedoptics scanning unit forming part of the scanning engine of FIG. 2;

FIG. 4 is a simplified illustration of optical switching apparatusconstructed and operative in accordance with a preferred embodiment ofthe present invention;

FIG. 5 is a simplified illustration of an optical cross-connect assemblysuitable for use in the optical switching apparatus of FIG. 4;

FIGS. 6A and 6B illustrate two alternative embodiments of an integratedoptics switching unit forming part of the cross-connect assembly of FIG.5;

FIG. 7 is a simplified pictorial illustration of an integrated opticsbeam deflection unit useful as part of an integrated optics scanningunit of the type shown in FIGS. 3A and 3B or as part of an integratedoptics switching unit of the type shown in FIG. 6A or 6B;

FIGS. 8A and 8B illustrate a waveguide unit useful as part of theintegrated optics beam deflection unit of FIG. 7;

FIGS. 9A, 9B, 9C and 9D are graphs illustrating the far-fielddiffraction pattern produced by an optical beam deflector constructedand operative in accordance with a preferred embodiment of the presentinvention for different applied voltages;

FIG. 10 is a simplified illustration of a multiplexer providingsequential voltage inputs to multiple waveguides forming part of a beamdeflection unit in accordance with a preferred embodiment of the presentinvention;

FIG. 11 is a graph illustrating the wavelength dependency of the angularlocation of diffraction produced in accordance with a preferredembodiment of the present invention;

FIG. 12 is a simplified illustration of wave division multiplexingapparatus constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 13 is a simplified flowchart illustrating the manufacture of awaveguide device in accordance with a preferred embodiment of thepresent invention;

FIGS. 14A, 14B, 14C, 14D and 14E are illustrations of various stages inthe manufacture of the waveguide device in accordance with the steps setforth in FIG. 13;

FIG. 15 is a simplified illustration of a polarization-independentwaveguide constructed and operative in accordance with a preferredembodiment of the present invention;

FIGS. 16A, 16B and 16C are illustrations of the operational parametersof the waveguide of FIG. 15;

FIG. 17 is a simplified illustration of a polarization-independentwaveguide constructed and operative in accordance with another preferredembodiment of the present invention;

FIG. 18 is a simplified illustration of a polarization-independentwaveguide constructed and operative in accordance with yet anotherpreferred embodiment of the present invention;

FIG. 19 is a simplified illustration of a polarization-independentwaveguide constructed and operative in accordance with still anotherpreferred embodiment of the present invention;

FIG. 20 is a simplified illustration of an optimal waveguide structurefor a given wavelength in accordance with a preferred embodiment of thepresent invention;

FIG. 21 is a simplified illustration of part of a waveguide devicehaving multiple conductors constructed and operative in accordance witha preferred embodiment of the present invention;

FIG. 22 is a simplified illustration of a monolithic laser and waveguidestructure constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 23 is a simplified illustration of part of a waveguide devicehaving tapered inputs;

FIG. 24 is a simplified illustration of a waveguide device having amulti-mode interference coupler including a tapered input waveguide;

FIG. 25 is a simplified illustration of wave propagation in a waveguidedevice having a multi-mode interference coupler;

FIG. 26 is a simplified illustration of wave propagation in a waveguidedevice having a free-space input coupler;

FIG. 27 is a simplified illustration of an optical cross-connectassembly constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 28 is a simplified illustration of a monolithic device having bothelectronic and optical functionality;

FIG. 29 is a simplified illustration of part of an optical switchincluding a monolithic plurality of selectably directable optical beamdeflecting devices in accordance with one preferred embodiment of thepresent invention;

FIG. 30 is a simplified illustration of part of an optical switchincluding a monolithic plurality of selectably directable optical beamdeflecting devices in accordance with another preferred embodiment ofthe present invention;

FIG. 31 is a simplified illustration of part of an optical switchincluding a monolithic plurality of selectably directable optical beamdeflecting devices in accordance with yet another preferred embodimentof the present invention;

FIG. 32 is a simplified illustration of a waveguide device having alight coupler including a modulator associated with an input waveguide;

FIG. 33 is a simplified illustration of a beam deflector including awaveguide structure in accordance with a preferred embodiment of thepresent invention;

FIG. 34 is an illustration of operational parameters of a waveguidedevice having lens functionality in accordance with a preferredembodiment of the present invention;

FIG. 35 is a simplified illustration of part of an optical cross-connectassembly constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 36 is a simplified illustration of an optical cross-connectassembly constructed and operative in accordance with another preferredembodiment of the present invention;

FIG. 37 is a simplified illustration of an optical cross-connectassembly constructed and operative in accordance with yet anotherpreferred embodiment of the present invention;

FIG. 38 is a simplified illustration of an optical cross-connectassembly of the type shown in any of FIGS. 35-37 with feedbackfunctionality;

FIG. 39 is a simplified illustration of an optical cross-connectassembly constructed and operative in accordance with a preferredembodiment of the present invention;

FIG. 40 is a simplified illustration of an optical cross-connectassembly constructed and operative in accordance with another preferredembodiment of the present invention;

FIG. 41 is a simplified illustration of a waveguide filter constructedand operative in accordance with a preferred embodiment of the presentinvention; and

FIG. 42 is a simplified illustration of a monolithic opticalcross-connect assembly constructed and operative in accordance with apreferred embodiment of the present invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

Reference is now made to FIG. 1, which is a simplified illustration oflaser writing apparatus constructed and operative in accordance with apreferred embodiment of the present invention. The laser writingapparatus typically comprises a laser scanning unit 20, illustrated inFIG. 2, which writes a latent image 21 onto a photoreceptor 22, which istypically located on the cylindrical surface of a drum 23.

The photoreceptor 22, bearing the latent image 21, receives toner from atoner hopper 24 via a developer roller 26 and transfers the toner onto asubstrate 28 with the assistance of a transfer corotron 30. The toner isfused onto the substrate by a fuser 32. A discharge lamp 34 serves todischarge the photoreceptor 22. Downstream of discharge lamp 34, acharge corotron 36 uniformly charges the photoreceptor, upstream ofimpingement thereon of laser beams 37 from laser scanning unit 20, whichselectively discharges regions on the photoreceptor, thus creating thelatent image 21.

It is a particular feature of the present invention that the laserscanning unit 20, as illustrated in FIG. 2, comprises a selectablydirectable optical beam deflector including a base 50 onto which aremounted a plurality of substrates 52, each having formed thereon amultiplicity of waveguides 54, preferably 256 in number, each waveguide54 preferably receiving light and emitting light having a selectablephase, intensity or a combination thereof The totality of light emittedby the multiplicity of waveguides 54 on each substrate 52 is supplied toan output lens 55, which produces a selectably directable output beam56, which covers a given sector of the photoconductor. The varioussubstrates cooperate to cover the entire useful area of thephotoconductor.

It is a particular feature of the present invention that the substrates52 need not be aligned on base 50 to a very high degree of accuracy,inasmuch as the orientations of beams 56 produced thereby areelectronically determined and adjustable, inter alia to takemisalignment into account.

At least one sequential multiplexer 58 applies electrical inputs to eachsubstrate 52 for individually controlling the light emitted by each ofthe multiplicity of waveguides 54, thereby governing the orientation ofsaid selectably directable output beam 56. Preferably, the sequentialmultiplexer 58 is a phase controller which controls the phase of thelight emitted by each, of the multiplicity of waveguides. Alternativelymultiplexer 58 may be an intensity controller or a combinationphase/intensity controller. Multiplexer 58 may be on a substrateseparate from or integral with substrate 52.

An input light source 60, such as a diode laser or an optical fiber,provides a light beam 62 which impinges on an input lens assembly 64, apreferred embodiment of which is illustrated in FIG. 7. The input lensassembly 64 provides a multiplicity of focused beams 65, each of whichimpinges on one of the waveguides 54 on substrate 52.

As seen in FIG. 7, the input lens assembly 64 typically comprises acombination of a cylindrical lens 66 and an array of cylindricalmicrolenses 67 bonded thereto. The output lens 55 typically comprisesmutually perpendicularly aligned cylindrical lenses 68 and 69.

Reference is now made to FIGS. 3A and 3B, which illustrate twoalternative embodiments of an integrated optics scanning unit formingpart of the scanning engine of FIG. 2. In the embodiment of FIG. 3A, aninput laser 70, such as a diode laser, receives a laser control signalfrom content control electronics (not shown) and provides a laser beam72 which impinges on an input lens assembly 74, a preferred embodimentof which is illustrated in FIG. 7.

The input lens assembly 74 provides a multiplicity of focused beams 76,each of which impinges on one of the waveguides 54 on substrate 52. Eachwaveguide 54 receives an electrical input via a corresponding conductor78, which extends from the waveguide to a corresponding connector pad 80which is also formed on substrate 52. A sequential multiplexer 58 (FIG.2), formed on a separate substrate 82 receives address information viaan address bus 84 and a phase, intensity, or phase/intensity input viaan input line 86 from control electronics (not shown) and supplies aphase, intensity, or phase/intensity control signal to each waveguide 54via a conductor 88 and a corresponding connector pad 80 and conductor78.

The phase, intensity or phase/intensity controlled outputs 90 of each ofthe waveguides 54 are combined in an output lens 92 and produce afocused output beam 94, whose direction is controlled by the phase,intensity or phase/intensity inputs supplied via multiplexer 58.

The embodiment of FIG. 3B is identical to that of FIG. 3A other than inthat multiplexer 58 (FIG. 2) is not embodied on a separate substratefrom that on which the waveguides 54 are formed, as in FIG. 3A. In theembodiment of FIG. 3B, waveguides 54 and sequential multiplexer 58 areboth embodied on a single substrate 100 and thus connector pads 80 maybe eliminated. The remaining elements of FIG. 3B may be identical tothose in FIG. 3A and are indicated by the same reference numerals.

According to an alternative embodiment of the present invention, inputand output lenses 74 and 92 may be eliminated. Other types of opticalcouplers, known in the art, may be employed instead.

Reference is now made to FIG. 4, which is a simplified illustration ofoptical switching apparatus constructed and operative in accordance witha preferred embodiment of the present invention. The optical switchingapparatus preferably comprises an optical interconnect unit 110 which isconnected to a multiplicity of ports 112, most or each of which has adata output line 114, an address output line 116 and a data input line118, as well as a, preferably duplex, information conduit 120 which canbe of any suitable form, such as, for example, copper or fiber and whichcan receive data in any suitable format. Some of the ports 112 may lacka data input line or may lack a data output line and an address outputline.

When optical fibers are employed as data output lines 114, it ispreferred that polarization maintaining fibers be employed inconjunction with polarized lasers or other polarized light sources. Thiseliminates polarization sensitivity of the beam deflection.

Preferably clock synchronization is maintained between the input andoutput portions of each of ports 112 and between the various ports 112.

The optical interconnect unit 110, a preferred embodiment of which isillustrated in FIG. 5, comprises a beam deflector assembly array 122 anda beam receiving assembly array 124. Each beam deflector assembly inarray 122 receives data and address inputs from a port 112 and each beamreceiving assembly in array 124 provides a data input to a port 112.

It is a particular feature of the present invention that the opticalinterconnect unit 110, as illustrated in FIG. 5, comprises a selectablydirectable optical beam deflector including a base 150 onto which aremounted a plurality of substrates 152, each having formed thereon amultiplicity of waveguides 154, preferably 256 in number, each waveguide154 preferably receiving light and emitting light having a selectablephase. The totality of light emitted by the multiplicity of waveguides154 on each substrate 152 produces a selectably directable output beam156.

Also preferably mounted on base 150 is the beam receiving assembly array124. Each beam receiving assembly 158 preferably comprises a beamreceiving lens 160 which couples a received beam onto an output fiber162, which is preferably a flexible fiber. Alternatively, the outputfiber 162 may be replaced by a suitable light detector.

It is a particular feature of the present invention that the substrates152 and the beam receiving assemblies 158 need not be aligned on base150 to a very high degree of accuracy, inasmuch as the orientations ofbeams 156 produced thereby is electronically determined and adjustable,inter alia to take into misalignment into account.

At least one sequential multiplexer 168 applies electrical inputs toeach substrate 152 for individually controlling the light emitted byeach of the multiplicity of waveguides 154, thereby governing theorientation of the selectably directable output beam 156.

Preferably, the sequential multiplexer 168 is a phase controller whichcontrols the phase of the light emitted by each of the multiplicity ofwaveguides. Alternatively, multiplexer 168 is an intensity orphase/intensity controller.

Reference is now made to FIGS. 6A and 6B, which illustrate twoalternative embodiments of an integrated, optics switching unit formingpart of the cross-connect assembly of FIG. 5. In the embodiment of FIG.6A, an input optical fiber 170 provides a beam 172 which impinges on aninput lens assembly 174, a preferred embodiment of which is illustratedin FIG. 7.

The input lens assembly 174 provides a multiplicity of focused beams176, each of which impinges on one of the waveguides 154 on substrate152. Each waveguide 154 receives an electrical input via a correspondingconductor 178, which extends from the waveguide to a correspondingconnector pad 180 which is also formed on substrate 152. A sequentialmultiplexer 168 (FIG. 5), formed on a separate substrate 182, receivesaddress information via an address bus 184 and a phase, intensity orphase/intensity input via an input line 186 from control electronics(not shown) and supplies a phase, intensity or phase/intensity controlsignal to each waveguide 154 via a conductor 188 and a correspondingconnector pad 180 and conductor 178.

The phase, intensity or phase/intensity controlled outputs 190 of eachof the waveguides 154 are combined in an output lens 192 and produce afocused output beam 194, whose direction is controlled by the phase,intensity or phase/intensity inputs supplied via multiplexer 168.

The embodiment of FIG. 6B is identical to that of FIG. 6A other than inthat sequential multiplexer 168 (FIG. 5) is not embodied on a separatesubstrate from that on which the waveguides 154 are formed, as in FIG.6A. In the embodiment of FIG. 6B, waveguides 154 and sequentialmultiplexer 168 are both embodied on a single substrate 200 and thusconnector pads 180 may be eliminated. The remaining elements of FIG. 6Bmay be identical to those in FIG. 6A and are indicated by the samereference numerals.

Reference is now made to FIGS. 8A and 8B. FIG. 8A is a perspectiveillustration of a waveguide unit useful as part of the integrated opticsbeam deflection unit of FIG. 7, while FIG. 8B is a detailed sectionalillustration of a pair of waveguides forming part of the waveguide unitof FIG. 8A. It is seen from a consideration of FIGS. 8A and 8B thatsubstrate 52 (FIGS. 2 & 7) is, preferably formed of an N doped GaAslayer 250 having formed on the bottom thereof an N-type ohmic contact252, typically comprising evaporated Ni/GeAu/Ni/Au. Formed over layer250 is a cladding layer 254, preferably formed of N doped AlGaAs.

The waveguide 54 is based on layer 254 and includes a core layer 256comprising a GaAs PN junction defined by an N layer 258 and a P layer260. A cladding layer 262, preferably formed of P doped AlGaAs, ispreferably formed over layer 260. A cap layer 264, preferably formed ofP+ doped GaAs, is preferably formed over layer 262.

Along the length of the waveguides there are provided P-type ohmiccontacts 266, typically formed of Ti/Au. Adjacent waveguides 54 areseparated from each other by etching. The resultant gaps are indicatedby reference numeral 268.

A polyimide insulative layer 270 is preferably formed over layer 266,fills gaps 268, and defines intermittent discrete apertures 272.Intermitted strips of a metal layer 274 are formed over the polyimideinsulative layer 270 and contact the ohmic contacts 266 through discreteapertures 272 in the polyimide layer 270. The intermittent stripsprovide individual mutually insulated electrical pathways communicatingwith each of the waveguides 54 separately. These pathways are designatedby reference numeral 78 in FIGS. 3A and 3B and by reference numeral 178in FIGS. 6A and 6B.

It is appreciated that the depth of gaps 268 defined by etching may varysuch that layers 250, 254, 258 and 260 may or may not be etched todefine gaps and waveguides. It is to be appreciated that waveguides 54may also be provided by any other suitable technique, such as, forexample, ion implantation.

Waveguide structures of this general type are described in the followingpublication, and the references cited :therein, the disclosures of whichare hereby incorporated by reference:

J. G. Mendoza-Alvarez et al, Analysis of Depletion Edge TranslationLightwave Modulators, IEEE Journal of Lightwave Technology Vol. 6, No.Jun. 6, 1988, pp. 793-808.

Reference is now made to FIGS. 9A, 9B, 9C and 9D, which are graphsillustrating a simulation of the far-field diffraction and interferencepattern produced by an optical beam deflector constructed and operativein accordance with a preferred embodiment of the present invention fordifferent applied voltages. The simulation is for an optical beamdeflector which includes 256 waveguides having a pitch between adjacentwaveguides of 9 microns. The width of each waveguide is 3 microns andthe wavelength of the light passing through the deflector is 1.3microns.

FIGS. 9A, 9B, 9C and 9D illustrate the far-field diffraction andinterference patterns for phase shifts between adjacent waveguides of 0;π/2; π; and 3π/2, respectively.

It can be seen from a consideration of FIGS. 9A-9D that the relativephase of each of the waveguides determines the angular location of givenlobes of the interference pattern, while the diffraction pattern definesan intensity envelope which does not vary with phase but causesdifferent angular locations to have different intensities.

It is a particular feature of the present invention that the ratiobetween the angular width of each of the lobes and the angularseparation between adjacent lobes is very substantial, due to the factthat the invention enables a very large number of waveguides (typically256) to be formed on a substrate and individually operated.

This high ratio enables a correspondingly high level of resolution to berealized in various applications, such as scanning and switching,providing a high number of individually addressable scanning andswitching locations.

It may also be appreciated by persons skilled in the art that the peaksignal to background ratio is very high due to large number ofwaveguides employed.

Reference is now made to FIG. 10 which is an illustration of an opticalmultiplexer providing sequential voltage inputs to multiple waveguidesforming part of a beam deflection unit in accordance with a preferredembodiment of the present invention.

As seen in FIG. 10, each waveguide 54 intermittently receives anelectrical input via an electrical pathway, such as pathway 78 (FIGS. 3Aand 3B) or 178 (FIGS. 6A and 6B). The electrical input is preferablysupplied from the drain 301 of a FET transistor 300 whose gate 302 iscoupled to the output of an AND gate 304. The source of each FETtransistor 300 receives a phase, intensity or phase/intensity input froman analog voltage line 306, identified by reference numeral 86 in FIGS.3A and 3B and by reference numeral 186 in FIGS. 6A and 6B.

Each AND gate 304 receives a plurality of digital address inputs via NOTgates 308 from an address bus 310, which is identified by referencenumeral 84 in FIGS. 3A and 3B and by reference numeral 184 in FIGS. 6Aand 6B. Each AND gate 304 is differently configured such that everyavailable combination of address inputs causes a different single ANDgate to provide an electrical output to a corresponding gate of acorresponding FET transistor 300.

It is a particular feature of the present invention that the multiplexersequentially provides individual phase, intensity or phase/intensityinputs to the individual waveguides, using digital address coding, thusenabling a very large number of waveguides to be individually addressed.

Reference is now made to FIG. 11, which illustrates the wavelengthdependency of the angular location of the diffraction orders. Thiswavelength dependency may be employed advantageously in accordance witha preferred embodiment of the present invention to provide wavelengthdivision multiplexing (WDM). In this manner multiple informationchannels may be sent over a single physical fiber by transmitting eachchannel along a separate wavelength.

Reference is now made to FIG. 12, which illustrates wavelength divisionmultiplexing apparatus constructed and operative in accordance with apreferred embodiment of the present invention.

The wavelength division multiplexing apparatus 410 preferably comprisesa beam diffractor assembly array 422 and a beam receiving assembly array424. Each beam diffractor assembly in array 422 receives data andaddress inputs from a port and produces a light beam having multiplewavelength components and each beam receiving assembly in array 424provides a data input to a port.

It is a particular feature of the present invention that the wavelengthdivision multiplexing unit 410, as illustrated in FIG. 12, comprises anoptical beam diffractor, which preferably also operates as a selectablydirectable optical beam deflector and includes a base 450 onto which aremounted a plurality of substrates 452, each having formed thereon amultiplicity of waveguides 454, preferably 256 in number, each waveguide454 preferably receiving light and emitting light in a plurality ofbeams according to their wavelength. The totality of light emitted bythe multiplicity of waveguides 454 on each substrate 452 preferablyproduces a plurality of selectably directable output beams, hereindicated as beams 456 and 457.

Also preferably mounted on base 450 is the beam receiving assembly array424. Each beam receiving assembly 458 preferably comprises a beamreceiving lens 460 which couples a received beam onto an output fiber462, which is preferably a flexible fiber. Alternatively, the outputfiber 462 may be replaced by a suitable light detector. Each beamreceiving assembly preferably receives a beam of a different wavelength.

It is a particular feature of the present invention that the substrates452 and the beam receiving assemblies 458 need not be aligned on base450 to a very high degree of accuracy, inasmuch as the orientations ofbeams 456 produced thereby is electronically determined and adjustable,inter alia to take into misalignment into account.

Reference is now made to FIG. 13, which is a simplified flowchartillustrating the manufacture of a, waveguide device of the type shown inFIG. 8B, in accordance with a preferred embodiment of the presentinvention. As indicated in FIG. 13 a multi-layer gallium arsenide wafer,such as that illustrated in FIG. 8B and including layers 250, 254, 258,260, 262 and 264, is coated with metal to provide a layer such as layer252 (FIG. 8B). This initial stage is illustrated in FIG. 14A, whereinthe wafer is designated by reference numeral 500 and the metal layer isillustrated by reference numeral 502.

The waveguiding regions of the waver, e.g. layers 258, 260, 262 and 264(FIG. 8B) are configured preferably by standard photolithography andreactive ion etching. This stage is illustrated in FIG. 14B, where thewaveguiding regions are indicated by reference numeral 504.

It is a particular feature of the invention that the front side of thewafer, i.e. the top surfaces 506 of waveguiding regions 504 and the topsurfaces 508 of the recesses 510 therebetween, is selectively coatedwith metal by evaporation in a direction generally perpendicularthereto, the direction being selected with respect to interconnectingsurfaces 512 which interconnect the upper and lower surfaces 506 and 508respectively such that metal is not substantially coated onto theinterconnecting surfaces 512, whereby electrical connections between theupper and lower surfaces 506 and 508 via the interconnecting surfaces512 are not formed by the metal coating. The metal layer, which isdesignated by reference numeral 266 in FIG. 8B, is indicated byreference numeral 514 in FIG. 14C.

Following formation of 514 by evaporation as aforesaid, one or moreconductive layers, separated from each other and from metal layer 514 byinsulative layers, are preferably provided. A conductive layer isindicated in FIG. 8B by reference numeral 274 and in FIG. 14D byreference numeral 516 and an insulative layer is indicated in FIG. 8B byreference numeral 270 and in FIG. 14D by reference number 518. Vias 520are preferably provided to interconnect conductive layers, such as layer516, with layer 514 through insulative layer 518. As seen in FIG. 14E,the outlines of the monolithic device may then be defined by cleavingand dicing.

Reference is now made to FIG. 15, which is a simplified illustration ofa polarization-independent waveguide constructed and operative inaccordance with a preferred embodiment of the present invention. Thewaveguide of FIG. 15 is characterized in that it is formed of at leasttwo elongate portions 530 and 532, separated by a gap 534. Gap 534 ispreferably smaller than the wavelength of the light guided by thewaveguide. A DC voltage V1 of a first polarity is applied to elongateportion 530, while a DC voltage V2 of a second polarity, opposite to thefirst polarity, is applied to elongate portion 532. Gap 534 need not bea cut or other physical separation, but may be only an electrical orconductive separation.

It is known that the presence of an electric field in a gallium arsenidewaveguide changes the phase of light passing through the waveguide. Theresulting change in phase differs with the polarization of the light,whereby for a given electric field light of one polarization, such aslight in a TE mode is phase shifted more than light of polarizationperpendicular thereto, such as light in a TM mode.

It has been appreciated by the present inventors that by switching thedirection of the electric field, the effect thereof on light in the TEand TM modes is reversed. This can be seen from a consideration of FIGS.16A and 16B, which illustrate the phase shifts produced in mutuallyperpendicularly polarized light by electric fields of opposite polarity.

Thus, if an electric field in a first direction causes a greater phasechange for light in a TE mode than for light in a TM mode, an electricfield in a second direction, opposite to the first direction, causes agreater phase change for light in a TM mode than for light in a TE mode.

Accordingly, by first applying an electric field in a first direction tolight guided along the waveguide and then applying an electric field ina second direction, opposite to the first direction, to that light, theeffect of polarization on the phase change of the light is neutralized.This is visualized in FIG. 16C.

It is appreciated that the two electrical fields need not necessarily beopposite in order to neutralize the effect of polarization as aforesaid.The desired neutralization may be realized empirically even withelectric fields which are not opposite.

Reference is now made to FIG. 17, which is a simplified illustration ofa polarization-independent waveguide constructed and operative inaccordance with another preferred embodiment of the present invention.The waveguide of FIG. 17 is characterized in that it is formed of twoelongate portions 550 and 552 of identical length, separated by aquarter wave plate 554. The quarter wave plate is operative to rotatethe polarization direction of light guided along the waveguide by 90degrees, therefore shifting the TM component to a TE component and viceversa.

Thus light traveling along the entire waveguide has the same phasechange irrespective of its polarization upon entry to the waveguide.

Reference is now made to FIG. 18, which is a simplified illustration ofa polarization-independent waveguide constructed and operative inaccordance with yet another preferred embodiment of the presentinvention. In this embodiment, there is provided a selectably directableoptical beam deflecting device comprising a substrate 570 having formedthereon a multiplicity of electrically controlled, phase-shiftingwaveguides 572, such as waveguides of the type described hereinabovewith reference to FIGS. 8A and 8B.

In accordance with a preferred embodiment of the present invention thereis also formed on substrate 570 a light receiver 574 for directing lightinto the multiplicity of waveguides 572. Preferably, the light receivercomprises a selectable polarization rotator 576. In accordance with apreferred embodiment of the present invention, the selectablepolarization rotator is automatically operative to rotate thepolarization so as to provide an optimized light output from themultiplicity of waveguides.

Preferably, the selectable polarization rotator is responsive to anoutput of the multiplicity of waveguides. Alternatively, the selectablepolarization rotator is responsive to the polarization of an input tothe multiplicity of waveguides.

The selectable polarization rotator is preferably embodied in a galliumarsenide voltage controlled waveguide, which may be constructed in amanner similar or identical to that described hereinabove.

Reference is now made to FIG. 19, which is a simplified illustration ofa polarization-independent waveguide constructed and operative inaccordance with still another preferred embodiment of the presentinvention. This embodiment is characterized in that a polarizationrotator 590 rotates the polarization of light passing through amultiplicity of electrically controlled, phase-shifting waveguides 592by 90 degrees. Preferably, the polarization rotator 590 comprises amagnetic field source producing a magnetic field B, whose axis liesparallel to the longitudinal axes of the waveguides 592. The magneticfield B is typically produced by the flow of an electric current i, asshown in FIG. 19.

In this way, light guided along the waveguide has its polarizationshifted by 90 degrees, therefore shifting the TM component to a TEcomponent and vice versa.

Thus light traveling along the entire waveguide has the same phasechange irrespective of its polarization upon entry to the waveguide.

As in the embodiment of FIG. 18, in accordance with a preferredembodiment of the present invention, the selectable polarization rotator590 is automatically operative to rotate the polarization so as toprovide an optimized light output from the multiplicity of waveguides592.

Preferably, the selectable polarization rotator 590 is responsive to anoutput of the multiplicity of waveguides 592. Alternatively, theselectable polarization rotator 590 is responsive to the polarization ofan input to the multiplicity of waveguides 592.

Reference is now made to FIG. 20, which is a simplified illustration ofan optimal waveguide structure for a given wavelength in accordance witha preferred embodiment of the present invention. FIG. 20 illustrates anoptimal distribution of light in the waveguide of FIG. 8B. The lightintensity is illustrated by trace 598. Preferably, the waveguide isconstructed such that most of the light is confined in layers 256 (FIG.8B). Little or no light is to be allowed in conductive layers 266 and252. Techniques for confining light in layers 256 are well known in theart and need not be described herein.

It is additionally preferred that a P-N junction 600 be defined inlayers 256 as indicated in FIG. 8B.

Reference is now made to FIG. 21, which is a simplified illustration ofpart of a waveguide device having multiple conductors constructed andoperative in accordance with a preferred embodiment of the presentinvention. In the embodiment of FIG. 21, there is provided a substrate610 having formed thereon a multiplicity of phase-shifting waveguides612. A light receiver (not shown) directs light into the multiplicity ofwaveguides. The substrate 610 comprises multiple mutually insulatedconductor layers 614, which are insulated by insulative layers 616 andare connected to said waveguides by vias 618. Vias 618 are constructedlayer by layer and are interconnected via pads 620.

Reference is now made to FIG. 22, which is a simplified illustration ofpart of a monolithic laser and waveguide structure constructed andoperative in accordance with a preferred embodiment of the presentinvention. Such monolithic structure are believed to be novel. Thestructure of FIG. 22 preferably comprises a substrate 620 having formedthereon a multiplicity of waveguides 622, of which only one is shown,and a laser 624, monolithically formed on the substrate 620 andproviding light to the multiplicity of waveguides 622.

The laser 624 preferably is constructed in accordance with the foregoingdescription of FIG. 8B and includes:

an N-doped gallium arsenide substrate 626;

an N-doped aluminum gallium arsenide layer 628 formed over substrate626;

an N-doped gallium arsenide layer 630 formed over the N-doped aluminumgallium arsenide layer 628;

a P-doped gallium arsenide layer 632 formed over the N-doped galliumarsenide layer 630;

a P-doped aluminum gallium arsenide layer 634 formed over the P-dopedgallium arsenide layer 632; and

a P-doped gallium arsenide layer 636 formed over the P-doped aluminumgallium arsenide layer 634.

It is a particular feature of the present invention that the fact thatthe waveguide structure of FIG. 8B can be operated as a light source,enables greatly enhanced ease of alignment of the waveguide with respectto external optics, since the waveguide can produce a beam of lightduring alignment thereof.

Reference is now made to FIG. 23, which is a simplified illustration ofpart of a waveguide device having tapered inputs. The structure of FIG.23 can be used as part of a selectably directable optical beamdeflecting device and includes a substrate 650 having formed thereon amultiplicity of waveguides 652 and a light receiver 654 directing lightinto the multiplicity of waveguides at first ends thereof. The structureis characterized particularly in that the multiplicity of waveguides 652are outwardly tapered at said first ends thereof 656 at which lightenters the waveguides. Preferably, the light receiver employs acylindrical lens 658. It is appreciated that the structure of FIG. 23may be used as a light output structure and not only as a light inputstructure.

Reference is now made to FIG. 24, which is a simplified illustration ofa waveguide device having a multi-mode interference coupler including atapered input waveguide. The structure of FIG. 24 is an alternative tothe structure of FIG. 23 and includes a substrate 670 having formedthereon a multiplicity of waveguides 672. Here a light receiver 674comprising a multi-mode interference coupler 676 directs light into themultiplicity of waveguides 672.

Preferably, the multi-mode interference coupler comprises a fightreceiving waveguide 678 which includes a light receiving end 680 whichmay be outwardly tapered, Light which is received at light receiving end680 is typically coupled from an optical fiber 682. The optical fiber682 has preferably a matching output end 683 for coupling to thereceiving end 680.

Reference is now made to FIG. 25, which is a simplified illustration ofwave propagation in a waveguide device of the type shown in FIG. 24,having a multi-mode interference coupler. It is seen that in themulti-mode interference coupler, designated by reference numeral 690,the waves interfere both constructive and destructively. By suitablyselecting the dimensions of the multi-mode interference coupler 690, aswell known in the art, it can be ensured that constructive interferencetakes place at a number of locations 692 at the interface 694 betweenthe multi-mode interference coupler and the waveguide.

In accordance with a preferred embodiment of the present invention thewaveguides 696 are constructed such that their entrances 698 are alignedwith locations 692, thereby maximizing the coupling efficiency betweenthe multi-mode interference coupler 690 and the waveguides 696.

In accordance with a preferred embodiment of the present invention, theinput waveguide 700 to the multi-mode interference coupler 690 may beoperative as an electro-absorption modulator, the functionality of whichis well-known in the art.

Reference is now made to FIG. 26, which is a simplified illustration ofwave propagation in a waveguide device having a free-space input coupler710. The waveguide device may be identical to that of FIGS. 24 and 25 instructure and function other than in that the dimensions of thefree-space input coupler 710 are not such that interference occurstherewithin. Rather the light propagates freely therethrough as shown tothe interface 712 with waveguides 714. In accordance with a preferredembodiment of the present invention, the entrance 716 of each waveguide714 is outwardly tapered, so as to enhance coupling efficiency.

As seen in FIG. 27, the waveguide devices described hereinabove withreference to FIGS. 23, 24, 25 and 26 may be employed in optical switchesboth as selectably directable optical beam deflection devices 730 at theinput end 734 and as selectably directable receiving devices 736 at theoutput end 738.

Reference is now made to FIG. 28, which is a simplified illustration ofa monolithic device having both electronic and optical functionality.The embodiment of FIG. 28 provides an active optical beam transmissiondevice comprising at least one substrate 750 having formed thereon amultiple layer integrated electronic circuit 752 and a multiplicity ofelectrically: controlled waveguides 754.

In accordance with a preferred embodiment of the present invention, thewaveguides 754 emit a selectably directable beam of light or selectablyreceive a beam of light.

Reference is now made to FIG. 29, which is a simplified illustration ofpart of an optical switch including a monolithic plurality of selectablydirectable optical beam deflecting devices 760 in accordance with onepreferred embodiment of the present invention. It is thus appreciatedthat in the embodiment of FIG. 29 all of the devices 760 are formed on asingle substrate 762. Each of devices 760 may be substantially identicalto the devices described hereinabove with reference to either of FIGS.23 and 24.

In the embodiment of FIG. 29, the electronic connection pads 764 arelocated adjacent each individual device 760.

FIG. 30 is a simplified illustration of part of an optical switchincluding a monolithic plurality of selectably directable optical beamdeflecting devices in accordance with another preferred embodiment ofthe present invention. It is similar to the embodiment of FIG. 29 otherthan in that the electronic connection pads 774 for all of theselectably directable optical beam deflecting devices 776 are alllocated adjacent the edges 778 of the common substrate 780.

Reference is now made to FIG. 31, which is a simplified illustration ofpart of an optical switch including a monolithic plurality of selectablydirectable optical beam deflecting devices in accordance with yetanother preferred embodiment of the present invention. Here, theelectrical connection pads 794 are formed over part of the selectablydirectable optical beam deflecting waveguide devices 796.

Reference is now made to FIG. 32, which is a simplified illustration ofa waveguide device having a light coupler 800, of the type describedhereinabove with reference to any of FIGS. 24-26 including an inputwaveguide 802 functioning as an electro-absorption modulator. Theembodiment of FIG. 32 also includes a light detector 804 providing amodulating output 806 to the electro-absorption modulator waveguide 802.Preferably, the light detector 804 receives a light input from aninformation carrying modulated light source 808.

The electro-absorption modulator waveguide 802 of FIG. 32 may serve asan electro-absorption modulator in the embodiments of FIGS. 24-26. Thelight detector 804 is preferably monolithically formed together with theelectro-absorption modulator waveguide 802 on the same substrate.

Reference is now made to FIG. 33, which is a simplified illustration ofa beam deflector including a waveguide structure in accordance with apreferred embodiment of the present invention. The beam deflector ofFIG. 33 is characterized in that it includes a spherical output lens 820which receives light from a cylindrical lens 822. Cylindrical lens 822is optically coupled to a multiplicity of waveguides 824 and isoperative to direct the light received from waveguides 824 in adirection perpendicular to the plane of waveguides 824. The sphericaloutput lens 820 focuses the light received from the cylindrical lens822.

Similarly to the structure described above with reference to FIG. 23,the waveguides 824 receive light from a cylindrical lens 826 which, inturn, receives light from the end 828 of an optical fiber 830.Alternatively, the input structure of the waveguides 824 may be similarto that described above with reference to FIG. 24.

Reference is now made to FIG. 34, which is an illustration ofoperational parameters of a waveguide device having lens functionalityin accordance with a preferred embodiment of the present invention FIG.34 indicates that by suitable selection of the electrical inputs to thewaveguide device of FIG. 33, the focusing functionality of the sphericallens 820 can be provided by the waveguides 824 and the spherical lens820 can be obviated.

Thus, it is appreciated that there is thus provided an opticalwaveguide-lens including a substrate having formed thereon amultiplicity of electrically controlled, phase-shifting waveguides andan electrical control signal source providing electrical signals to themultiplicity of waveguides to cause them to have a desired lensfunctionality.

FIG. 34 shows the phase shift produced by the electrical control signalas a function of the waveguide number. It is seen that a lensfunctionality, a tilt functionality and a combined lens and tiltfunctionality may be realized by suitable selection of electricalcontrol signals. It is, appreciated that the lens functionality, takenalone, or in combination with the tilt functionality may be employed inany and all of the embodiments of the invention described herein.

The present invention also provides an optical switch comprising aplurality of selectably directable optical beam deflecting devices and aplurality of optical beam receiving devices.

Reference is now made to FIG. 35, which is a simplified illustration ofpart of an optical cross-connect: assembly constructed and operative inaccordance with a preferred embodiment of the present invention. Theembodiment of FIG. 35 is particularly characterized in that it includesa plurality of selectably directable optical beam deflecting devices850, each comprising at least one substrate having formed thereon amultiplicity of waveguides. Optical beam deflecting devices of this typeare described hereinabove with reference to FIGS. 23 and 24.

The embodiment of FIG. 35 is also particularly characterized in that itincludes a plurality of optical beam receivers 852. Optical beamreceivers 852 may be optical fiber ends, as seen in FIG. 35. The opticalfibers may be single mode or multi-mode fibers and their ends may havesmall numerical apertures. Alternatively, optical beam receivers 852 maybe light detectors or selectably directable light receivers, asdescribed hereinabove with reference to FIG. 27.

In the embodiment of FIG. 35, at an input side 854, a plurality ofselectably directable optical beam deflecting devices 850 is arranged,each to receive light from a suitably positioned optical fiber end 856.It is noted that devices 850 are mounted on a substrate 858, such as amulti-layer ceramic substrate, onto which are also mounted controlelectronics 860.

Light coupling between optical fiber ends 856 and beam deflectiondevices 850 may be achieved using a microlens array 862, as shown. Themicrolens array 862 may comprise a combination of cylindrical lensesarranged in two perpendicular directions. The microlens array 862provides focusing in two mutually perpendicular directions withdifferent optical power. Where devices 850 are similar to thosedescribed in FIG. 23, the microlens array 862 provides output beamswhich are collimated in a direction parallel to the plane of the devices850. Where devices 850 are similar to those described in FIG. 24, themicrolens array 862 provides output beams which are focused in adirection parallel to the plane of the devices 850.

Although a single row of cylindrical lenses is shown in FIG. 35, it isappreciated that a double row of cylindrical lenses may alternatively beemployed.

Alternatively, the microlens array 862 may be obviated and individuallenses may be formed or mounted onto the optical fiber ends 856.

Downstream of the plurality of selectably directable optical beamdeflecting devices 850 there is provided one or more cylindrical lenses864 which have essentially the same functionality as that provided bycylindrical lens 822 in the embodiment of FIG. 33. A spherical lens 866receives light from the one or more cylindrical lenses 864 and has thefunctionality of spherical lens 820 in the embodiment of FIG. 33.Similarly to spherical lens 820, it may be obviated in a case where theplurality of selectably directable optical beam deflecting devices 850are provided with a lens functionality.

It is appreciated that the input side 854 may function as an output siderather than an input side. In such a case, the structures, such asoptical fiber ends, functioning as light receivers 852 may functioninstead as light transmitters. The light transmitters may be static ordirectable.

Reference is now made to FIG. 36, which is a simplified illustration ofan optical cross-connect assembly constructed and operative inaccordance with another preferred embodiment of the present invention.The optical cross-connect assembly of FIG. 36 is particularlycharacterized in that it includes a plurality of monolithic pluralities870 of selectably directable optical beam deflecting devices 872, aswell as a plurality of optical beam receiving devices 874. Theselectably directable optical beam deflecting devices 872 may be any ofthe devices described herein with reference to FIGS. 23-34. Themonolithic pluralities 870 may be any of the structures describedhereinabove with reference to FIG. 35.

In accordance with a preferred embodiment of the present invention, theplurality of monolithic pluralities 870 of beam deflecting devices 872are arranged generally parallel to one another along an axis 876perpendicular to a plane in which selectable deflection of a light beamis produced thereby, which is the plane of each of the plurality ofmonolithic pluralities 870.

A focusing lens 878 receives light from the plurality of monolithicpluralities 870 of beam deflecting devices 872 and focuses it onto thelight receiving devices 874. The lens 878 may be one or more lenses andmay have the functionality of lens 820 in the embodiment of FIG. 33. Assuch, it may be obviated by inclusion of lens functionality in theplurality of monolithic pluralities 870 of beam deflecting devices 872.

It is appreciated that the plurality of monolithic pluralities 870 ofbeam deflecting devices 872 and lens 878 may alternatively function aslight receivers rather than a light transmitter. In such a case, thestructures, such as optical fiber ends, functioning as light receivers874 may function instead as light transmitters. The light transmittersmay be static or directable.

Reference is now made to FIG. 37, which is a simplified illustration ofan optical cross-connect assembly constructed and operative inaccordance with yet another preferred embodiment of the presentinvention. The optical cross-connect assembly of FIG. 37 is particularlycharacterized in that it includes a plurality of monolithic pluralities880 of selectably directable optical beam deflecting devices 882, aswell as a plurality of optical beam receiving devices 884. Theselectably directable optical beam deflecting devices 882 may be any ofthe devices described herein with reference to FIGS. 23-34. Themonolithic pluralities 880 may be any of the structures describedhereinabove with reference to FIG. 35.

Here the plurality of monolithic pluralities 880 of beam deflectingdevices 882 are arranged generally distributed along a curve 886extending in a plane perpendicular to a plane in which selectabledeflection of a light beam is produced thereby, which is the plane ofeach of the plurality of monolithic pluralities 880.

A focusing lens 888 receives light from the plurality of monolithicpluralities 880 of beam deflecting devices 882 and focuses it onto thelight receiving devices 884. The lens 888 may be one or more lenses andmay have the functionality of lens 820 in the embodiment of FIG. 33. Assuch, it may be obviated by inclusion of lens functionality in theplurality of monolithic pluralities 880 of beam deflecting devices 882.

It is appreciated that the plurality of monolithic pluralities 880 ofbeam deflecting devices 882 and lens 888 may alternatively function aslight receivers rather than a light transmitter. In such a case, thestructures, such as optical fiber ends, functioning as light receivers884 may function instead as light transmitters. The light transmittersmay be static or directable.

Reference is now made to FIG. 38, which is a simplified illustration ofan optical cross-connect assembly of the type shown in any of FIGS.35-37 with feedback functionality. The embodiment of FIG. 38 comprisesan optical switch input end 900 which receives modulated light from amultiplicity of fibers 902 and selectably transmits the modulated lightto a multiplicity of light receivers 904, such as optical fiber ends.The switch input end 900 may be any suitable switch input end of thetype described herein with reference to any of FIGS. 35, 36 & 37.

Signal pickup devices 906 receive at least one parameter of the signalsreceived by light receivers 904 and provide feedback input signals to afeedback processor 908. Output signals from the feedback processor 908are operative to govern at least one parameter of the operation of theoptical switch input end 900.

This feedback arrangement provides reduced crosstalk and enhancedtransmission efficiency.

The feedback input signals to feedback processor 908 may representreceived signal intensity and crosstalk. The parameters of operation ofthe optical switch input end 900 which are affected by output signalsfrom the feedback processor include the phase shift produced byindividual waveguides, the amount of rotation produced by thepolarization rotator, such as rotator 576 (FIG. 18) or rotator 590 (FIG.19). The feedback processor 908 effectively provides a feedbackconnection between the optical beam receiving devices and the opticalbeam deflecting devices.

It is appreciated that the feedback functionality need not necessarilybe automatic but rather may involve some operator intervention.

Reference is now made to FIG. 39, which is a simplified illustration ofan optical cross-connect assembly constructed and operative inaccordance with a preferred embodiment of the present invention. Hereoptical beam receiving devices 910 are configured to receive light overa region 912 sufficiently large such that wavelength dependencies ofoptical beam deflectors 914 do not substantially affect the amount oflight sensed by the receiving devices.

Reference is now made to FIG. 40, which is a simplified illustration ofan optical cross-connect assembly constructed and operative inaccordance with a preferred embodiment of the present invention. Here amultiplicity of waveguides 920 are each operative simultaneously todeflect a plurality of optical beams 922 and to direct them to aplurality of different receivers 924.

Reference is now made to FIG. 41, which is a simplified illustration ofa waveguide filter constructed and operative in accordance with apreferred embodiment of the present invention. The waveguide filter ofFIG. 41 comprises a necked waveguide 930 having a relatively broad inputend 932 which receives light and allows propagation of multi-mode lightwaves therethrough. When the multi-mode light waves encounter a narrowedneck portion 934, the higher modes radiate outside the waveguide andonly the modes which can propagate through the neck portion 934 passtherethrough to a relatively broad output end 936. This filter can beused to efficiently remove higher modes which can cause crosstalk.

It is appreciated that the structures of FIGS. 39, 40 and 41 may beapplied to any of the optical beam deflectors, optical beam receivers,cross-connect assemblies and optical switches described herein.

Reference is now made to FIG. 42, which is a simplified illustration ofa monolithic optical cross-connect assembly constructed and operative inaccordance with a preferred embodiment of the present invention. Aplurality of selectably directable optical beam deflecting devices 950and a plurality of optical beam receiving devices 952 are allmonolithically formed on the same substrate 954.

It will be appreciated by persons skilled in the art that the presentinvention is not limited to.what has been particularly shown anddescribed hereinabove. Rather the scope of the present inventionincludes both combinations and subcombinations of various featuresdescribed hereinabove and shown in the drawings as well as modificationsthereto and variations thereof which would occur to a person skilled inthe art upon reading the description and which are not in the prior art.

What is claimed is:
 1. A monolithic optical light modulator comprising agallium arsenide substrate comprising layers of materials arranged toconfine an electrical field in a relatively small thickness and whereinthe said layers include: an N-doped gallium arsenide substrate; anN-doped aluminum gallium arsenide layer formed over said substrate; anN-doped gallium arsenide layer formed over the N-doped aluminum galliumarsenide layer; a P-doped gallium arsenide layer formed over the N-dopedgallium arsenide layer; a P-doped aluminum gallium arsenide layer formedover the P-doped gallium arsenide layer; and a P-doped gallium arsenidelayer formed over the P-doped aluminum gallium arsenide layer; andhaving formed monolithically thereon: a modulator; and a light detectorproviding a modulating output to said modulator.
 2. An optical lightmodulator according to claim 1 and wherein said modulator comprises awaveguide comprising at least one substrate having formed thereon anintegrated electronic circuit.
 3. An optical light modulator accordingto claim 2 and wherein said waveguide emits a selectably directable beamof light.
 4. An optical light modulator according to claim 2 and whereinsaid waveguide selectably receives a beam of light.
 5. An optical lightmodulator according to claim 2 and wherein said waveguide forms apolarization controller.
 6. An optical light modulator according toclaim 1 and comprising at least one substrate having formed thereon: aplurality of waveguide assemblies, each including a multiplicity ofelectrically controlled waveguides; and overlying each of said waveguideassemblies, a multiplicity of electrical contacts, each contactproviding an electrical connection to at least one of the multiplicityof electrically controlled waveguides in said assembly.
 7. An opticallight modulator according to claim 1 and wherein said modulatorcomprises a waveguide filter including: a necked waveguide having: arelatively broad input end which receives light and allows propagationof multi-mode light waves therethrough; a narrowed neck portion at whichhigher modes radiate outside the waveguide and only the modes which canpropagate therethrough pass therethrough; and a relatively broad outputend.
 8. An optical light modulator according to claim 1 and wherein saidmodulator comprises an optical waveguide-lens including: at least onesubstrate having formed thereon a multiplicity of electricallycontrolled, phase-shifting waveguides; and an electrical control signalsource providing electrical signals to said multiplicity of waveguidesto cause them to have a desired lens functionality.
 9. An optical lightmodulator according to claim 1 and wherein said modulator comprises aselectably directable optical beam generating device including: at leastone substrate having formed thereon a multiplicity of waveguides; and alaser monolithically formed on said at least one substrate and providinglight to said multiplicity of waveguides.
 10. An optical light modulatoraccording to claim 9 and wherein said multiplicity of waveguides andsaid laser are formed at different regions of identical layers.
 11. Anoptical light modulator according to claim 9 and wherein saidmultiplicity of waveguides have first ends which abut a planarwaveguide.
 12. An optical light modulator according to claim 9 and alsocomprising an electro-absorption modulator.
 13. An optical lightmodulator according to claim 12 and wherein said electro-absorptionmodulator receives a modulating input from a light detectormonolithically formed therewith on said at least one substrate.
 14. Anoptical light modulator according to claim 9 and wherein saidmultiplicity of waveguides is controllable so as to selectably providemultiple selectably directed output beams.
 15. An optical lightmodulator according to claim 9 and wherein said at least one substratehas formed thereon a multiplicity of electrically controlled,phase-shifting waveguides and wherein said device also comprises: anelectrical control signal source providing electrical signals to saidmultiplicity of waveguides to cause them to have a desired lensfunctionality.
 16. An optical light modulator according to claim 9 andalso comprising an electrical control signal source providing electricalsignals to said multiplicity of waveguides to cause them to have adesired lens functionality.
 17. An optical light modulator according toclaim 12 and wherein said multiplicity of waveguides is controllable soas to selectably provide multiple selectably directed output beams.